This invention relates to an air chamber mounting arrangement for brakes and more particularly to an improved arrangement for mounting the actuating element of a brake of the drum type.
In many popular forms of drum-type brakes, the brake shoes are activated by means of a cam mechanism that is interposed between adjacent ends of the brake shoes. The cam element may act either directly upon the brake shoes or may act on the brake shoe through an intermediate actuating mechanism including slidably supported tappets. In the application of this brake, the cam is rotated by means of a camshaft to which the cam is fixed and which camshaft extends through the backing or torque plate of the brake. The camshaft has a lever affixed to this exposed end and this lever is activated by means of a power unit that is mounted on the backing plate by means of a mounting bracket. In commercial vehicle applications, the power unit may comprise an air cylinder or air chamber.
Although the described type of brake is particularly advantageous, the mounting arrangement for the activating device cam present certain difficulties. For example, it is necessary for the mounting bracket to be affixed to the backing plate and for the power unit to be mounted to the mounting bracket. With previously proposed types of constructions, the configuration chosen for ease of assembly on the OEM assembly line has made servicing a problem. For example, it has been necessary to remove the brake drum and, in some instances, other components of the brake mechanism in order to access the mounting studs or bolts for the mounting bracket to permit removal and servicing. Obviously, this is not advantageous.
Furthermore, the mounting bolts or studs for affixing the power unit to the mounting bracket have been positioned so that their axes extend either parallel to the axes of rotation of the associate wheel, or alternatively, lie in a common plane that is perpendicular to this axis. As a result of this orientation, the natural vibrations about the wheel rotational axis can cause harmonic vibrations in the mounting assembly and associated difficulties.
It is, therefore, a principle object of this invention to provide an improved mounting arrangement for the power unit for a drum-type brake.
It is a further object of this invention to provide an improved mounting arrangement for a drum-type brake power unit wherein the power unit is mounted in such a way that mounting fasteners do not lie in a plane that is either parallel to or perpendicular to the rotational axis of the associated wheel or brake drum.
It is a still further object of this invention to provide an improved mounting arrangement for the power unit of a drum brake that facilitates servicing and will permit removal of the components without necessitating disassembly of the brake per se.